Liquid fuel burning heaters



LIQUID FUEL BURNING HEATERS Filed April 15, 1965 FIG. 1.

2 Sheets-Sheet 1 lllllllllllllllllllllllll! INVENTOILS HUGH CHBRLES HEBARD BE'RTRAM STANLEY BEARING Feb. 6, 1968 HEBARD ET AL 3,367,317

LIQUID FUEL BURNING HEATERS 2 Sheets-Sheet 2 Filed April 15, 1965 lAlvfih TnR Hue-H memes HEBARD BERTRAM STANLEY DE/lfilA/G- 8 Au a 5 United States Patent 3,367,317 LIQUID FUEL BURNING HEATERS Hugh Charles Hehard, Flackwell Heath, High Wycombe, and Bertram Stanley Dear-ing, Ickenham, England, assignors to Aladdin Industries Limited, Greeuford, England Filed Apr. 15, 1965, Ser. No. 448,489 Claims priority, application Great Britain, Apr. 21, 1964, 16,468/64 Claims. (Cl. 126--96) This invention relates to liquid fuel burning heaters and particularly to domestic heating appliances of the radiating type in which a radiant burner, for example, of the short drum or kindler type is situated in front of a reflector.

Oil heaters fitted with radiant burners of the short drum type can be sensitive to draughts and for satisfactory operation the burner must be adequately protected from the adverse effects of stray draughts. In the past, this has commonly been done by shrouding the burner, leaving a small entry near the base to admit the necessary air for combustion. With such as arrangement it has been found possible to subject the heater to frontal draughts of a considerable magnitude without unduly upsetting the burner, but lesser draughts from oblique angles or from the rear of the heater often have serious effects on the performance of the burner. Other arrangements have been used in which the burner is located in a complete pot with only the top of the burner exposed. Whilst this can be made effective against draughts in most directions, air for combustion has to be taken in at the top of the pot and drawn down to the base of the burner which causes some restriction in the amount of air entering the base of the burner. In consequence, if the burner is operated at low output for some time and the control valve is then suddenly opened to its fullest extent, the supply of cool air to the base of the burner may be insufficient, with the result that the burner may light on the wrong side of the shells and burn with a smoky flame.

The principal object of this invention is to provide encasement of the burner which renders it immune to the adverse effects of draught from any direction, whilst at the same time making adequate provision for the entry of sufficient cool air to ensure satisfactory operation when the control valve is suddenly opened from a low setting to the maximum flame position.

According to the invention in its broadest aspect, there is provided in a liquid fuel burning heater of the radiant type an enclosure of the burner which is formed with a slot for the entrance of combustion air to the burner, the vertical location of the slot being approximately the same as that of the top of the burner and the profile of the slot being similar to that of the reflector.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a front elevation of the lower half of the heater, and

FIG. 2 is a plan view of the heater.

In this embodiment, the burner-of the aforesaid short drum type comprising inner and outer shells 1 and 2, a casing 3 and a wick trough 4-is located near the focus of a large parabolic reflector 5 attached to the base 6 of the heater by a substantially vertical extension 7 of the reflector. The burner is shrouded by an enclosure comprising a bowed front piece 8 making substantially airtight contact with the base of the heater together with an inclined cover 9 with a hole in it through which the top portion of the burner projects. Air for combustion enters the burner casing through a slot 10 in the top cover in front of, and following the profile of, the base of the reflector. The burner is also surrounded by a spaced cylindrical tube 11 attached to the top cover which extends from just below the top of the burner to a point substantially level with the bottom of the casing 3 of the burner. This tube is open at the bottom and heat from the burner induces a draught up the annular passage between the burner casing and the tube which draws air into the burner enclosure through the slot 10 in front of the reflector. Since the temperature at the ends of this slot is considerably less than at the middle, there is a tendency for air to be drawn in at the extremities of the slot, thus ensuring an adequate supply of cool air for the burner.

When the heater is subjected to strong draughts, since the location of the air inlet slot is not very different from that of the top of the burner, no great pressure difference between the top and the bottom of the burner exists in the presence of draughts from any direction and with such an arrangement the heater is substantially proof against the adverse effects of stray draughts.

What is claimed is:

1. In a liquid fuel-burning heater having an enclosure, a cover on said enclosure, a reflector extending upwardly from said enclosure, a radiant burner having a lower portion shrouded by said enclosure and an upper portion extending through an aperture in the cover of said enclosure in front of said reflector, said enclosure being cut away adjacent to said reflector to form a narrow slot following the profile of said reflector for admitting burner combustion air into the chamber defined by said enclosure, and means at said aperture defining an annular draft inducing passage having its lower end open to said chamber within said enclosure and extending in surrounding relation to said burner to dispose its upper open end adjacent the top of said upper portion of the burner whereby a draft is induced by burner heat to draw air into said enclosure through said slot and upwardly from said chamber through said passage, the upper open end of said passage and said slot being disposed at closely adjacent vertical levels in the heater so that the effect of air pressure variations due to external drafts is substantially the same at said slot and said upper end of the passage.

2. The liquid fuel-burning heater defined in claim 1 wherein said burner is provided with a cylindrical casing, and said means defining said passage comprises a cylindrical open ended tube extending in peripherally surrounding spaced relation to said casing from within said chamber to the immediate vicinity of the top of said burner.

3. In a liquid fuel-burning heater having an enclosure, a reflector extending upwardly from said enclosure, and a radiant burner having a lower portion shrouded by said enclosure and an upper portion extending through an aperture in said enclosure in front of said reflector, said enclosure being cut away adjacent to said reflector to form a narrow slot following the profile of said reflector for admitting combustion air into the chamber defined by said enclosure, said burner comprising a cylindrical casing and a cylindrical open-ended tube extending through said aperture and peripherally surrounding the said casing to cooperate therewith for defining an annular passage up which a draft is induced by burner heat to draw air into said enclosure through said slot, and said slot extending appreciably at both ends beyond said burner to enable air essentially unheated by said burner to be drawn through the extremities of said slot.

4. The liquid fuel-burning heater defined in claim 3 wherein said enclosure comprises a front portion disposed 3 4 forwardly of said reflector and a cover delimiting the References Cited top of said chamber and extending between said reflector FOREIGN PATENTS and said front portion, said aperture being formed in the top portion of said cover and said slot being formed in 824,691 12/1959 Great m said cover at the rearward edge thereof adjacent to said 5 L146 2/1961 Great m refiecton 955,592 4/1964 Great Br1ta1n.

5. The liquid fuel-burning heater defined in claim 4 wherein said burner is provided at its lower portion with a fuel trough disposed below the bottom edge of said ROBERT DUA, Examinertube- 10 E. G. FAVORS, Assistant Examiner.

FREDERICK L. MA'ITESON, IR., Primary Examiner. 

1. IN A LIQUID FUEL-BURNING HEATER HAVING AN ENCLOSURE, A COVER ON SAID ENCLOSURE, A REFLECTOR EXTENDING UPWARDLY FROM SAID ENCLOSURE, A RADIANT BURNER HAVING A LOWER PORTION SHROUDED BY SAID ENCLOSURE AND AN UPPER PORTION EXTENDING THROUGH AN APERTURE IN THE COVER OF SAID ENCLOSURE IN FRONT OF SAID REFLECTOR, SAID ENCLOSURE BEING CUT AWAY ADJACENT TO SAID REFLECTOR TO FORM A NARROW SLOT FOLLOWING THE PROFILE OF SAID REFLECTOR TO FORM A NARROW SLOT COMBUSTION AIR INTO THE CHAMBER DEFINED BY SAID ENCLOSURE, AND MEANS AT SAID APERTURE DEFINING AN ANNULAR DRAFT INDUCING PASSAGE HAVING ITS LOWER END OPEN TO SAID CHAMBER WITHIN SAID ENCLOSURE AND EXTENDING IN SURROUNDING RELATION TO SAID BURNER TO DISPOSE ITS UPPER OPEN END ADJACENT THE TOP OF SAID UPPER PORTION OF THE BURNER WHEREBY A DRAFT IS INDUCED BY BURNER HEAT TO DRAW AIR INTO SAID ENCLOSURE THROUGH SAID SLOT AND UPWARDLY FROM SAID CHAMBER THROUGH SAID PASSAGE, THE UPPER OPEN END OF SAID PASSAGE AND SAID SLOT BEING DISPOSED AT CLOSELY ADJACENT VERTICAL LEVELS IN THE HEATER SO THAT THE EFFECT OF AIR PERSSURE VARIATIONS DUE TO EXTERNAL DRAFTS IS SUBSTANTIALLY THE SAME AT SAID SLOT AND SAID UPPER END OF THE PASSAGE. 